Preparation method of tire sidewall rubber material

Abstract

The invention provides a preparation method of a tire sidewall rubber material, and belongs to the field of regenerated rubber material production. The preparation method comprises the following steps: feeding green reclaimed rubber into a second double-screw extruder through a conveying device, adding a material obtained by stirring and mixing a lignin composition into a mixing section of the extruder through a side feeding device, controlling the temperature of the extruder to be 100-155 DEG C, reacting for 3-5 minutes, feeding the material into a third single-screw extruder, and carrying out extrusion molding, so as to obtain the environment-friendly rubber material. Controlling the temperature of the screw extruder to be 70-85 DEG C, feeding zinc oxide, stearic acid and an anti-aging agent into the extruder through a feeding device, mixing for 2-4 minutes, discharging, feeding into a first internal mixer, adding sulfur and an accelerant, mixing until the temperature is 80-100 DEG C, discharging, batching out by an open mill, cooling and stacking. According to the invention, biomass is used as a waste rubber regeneration auxiliary agent to prepare green reclaimed rubber, lignin partially replaces white carbon black and is used as a rubber reinforcing agent, and the prepared tire sidewall rubber material is green, environment-friendly, small in odor, low in required energy consumption and small in environmental pollution.

Description

Technical Field

[0001] The invention relates to a regenerated rubber compound manufacturing technology, in particular to a method for preparing a tire sidewall compound, and belongs to the technical field of regenerated rubber manufacturing. Background Art

[0002] With the development of social economy, a large amount of waste rubber has been generated, which has brought great pressure to resources and the environment. How to efficiently and greenly recycle waste rubber is one of the great challenges currently faced by polymer science and the rubber industry. In the process of regenerating waste rubber, a certain amount of activator and softener are usually added. When the waste rubber powder is desulfurized and regenerated, the additives in the rubber itself will produce various organic volatile substances. The above-mentioned desulfurization additives will also cause the prepared recycled rubber to have an unpleasant odor. Part of these gases will be emitted during the production process, causing pollution to the environment, and part of them will remain in the rubber products. On the one hand, it will affect the overall performance of the rubber products. On the other hand, the gas will be slowly released during the subsequent use of the rubber, which will not only affect people's experience of use, but also cause certain harm to human health.

[0003] As people pay more and more attention to health, the requirements for the odor level of automobile tires are getting higher and higher, which has led to restrictions on the use of waste rubber in tires.

[0004] Chinese patent (202310850546.5 A low-odor, low-heat outer rubber composition, mixing method and tire) discloses a low-odor, low-heat outer rubber composition, mixing method and tire, which uses a natural rubber composite material to completely or partially replace natural rubber. The natural rubber composite material includes an antibacterial agent, which acts on microorganisms before the microorganisms decompose the non-rubber components, rather than adsorbing or removing the generated malodorous gases after the microorganisms decompose the non-rubber components, thereby eliminating the occurrence of natural rubber deterioration, mold, and odor from the root, and avoiding the malodorous gases generated by tires made of natural rubber. In this method, an antibacterial agent is used to reduce the generation of odor, and the process has many steps and takes a long time, which is not conducive to industrial production.

[0005] Chinese patent (202010621769.0 A method for reducing the odor of pneumatic tires and low-odor tires) discloses a method for reducing the odor of pneumatic tires and low-odor tires, including providing a rubber mixed solution; the rubber mixed solution includes an organic solvent for dissolving rubber and a rubber composition, and the rubber composition includes the following components by weight: 60 to 100 parts of butyl rubber; 0 to 40 parts of natural rubber; 30 to 70 parts of carbon black; 1 to 10 parts of cycloalkyl oil; 2 to 6 parts of zinc oxide; 1 to 3 parts of stearic acid; 2 to 6 parts of adhesive resin; 2 to 6 parts of dispersant; 0.5 to 2 parts of sulfur; the rubber mixed solution is applied to the surface of the unvulcanized green tire, and vulcanized to obtain a low-odor tire. This method requires a large amount of organic solvent to dissolve the rubber composition, and the organic solvent will directly evaporate into the air, which is very unfriendly to the environment.

[0006] Therefore, there is an urgent need for a method for preparing a tire sidewall rubber material that is green, environmentally friendly, low in odor, and low in energy consumption. Summary of the invention

[0007] The invention provides a new method for preparing tire sidewall rubber material, which uses biomass as a waste rubber regeneration aid and lignin as a rubber reinforcing agent to solve the technical problems of complex tire production process and strong odor in the prior art.

[0008] The method for preparing the tire sidewall rubber material according to the embodiment of the present invention comprises the following steps:

[0009] Step 1: Preparation of green recycled rubber: Put waste rubber powder, biomass A and biomass B into a stirring and mixing device according to a certain mass ratio, stir for 4-7 minutes, and when the material temperature reaches 110-130°C, discharge the material and send it to the first twin-screw extruder through a conveying device. Control the temperature of the screw extruder to 130°C-155°C, react for 2min-4min, and prepare green recycled rubber;

[0010] Step 2: Preparation of lignin composition: natural rubber, butadiene rubber, softener, lignin, white carbon black and silane coupling agent are put into a stirring and mixing device, stirred for 1-3 minutes, and discharged when the temperature of the rubber reaches 100°C-120°C;

[0011] The third step is to prepare the rubber compound for the tire sidewall; the rubber compound prepared in the first step is fed into the second twin-screw extruder through a conveying device, the material obtained by stirring and mixing in the second step is added into the mixing section of the extruder through a side feeding device, the temperature of the extruder is controlled to be 100°C-155°C, the reaction is carried out for 3min-5min, the material is fed into the third single-screw extruder, the temperature of the screw extruder is controlled to be 70°C-85°C, zinc oxide, stearic acid and antioxidant are put into the extruder through a feeding device, mixed for 2-4min and then discharged, fed into the first internal mixer, sulfur and accelerator are added, mixed to 80-100°C and discharged, and the tire sidewall rubber compound is obtained by opening the mixer;

[0012] In the first step, the mass ratio of waste rubber powder, biomass A and biomass B is 100:3-10:4-8; the waste rubber powder is a mixture of any one or more of waste tire full tire rubber powder and waste tire tread rubber powder, and the mesh size of the waste rubber powder is 20-80 meshes; biomass A is a plant regeneration agent, including any one or more of garlic juice and lemon peel juice; biomass B is any one or more of soybean oil, castor oil, rapeseed oil and palm oil.

[0013] The method for preparing the tire sidewall rubber compound as described above, wherein the aspect ratio of the screw of the first twin-screw extruder in the first step is 24-32:1.

[0014] The method for preparing the tire sidewall rubber compound as described above, wherein in the third step, the mixing section temperature of the second twin-screw extruder is 110°C-125°C, the reaction section temperature is 145°C-155°C, the cooling section temperature is 110°C-120°C, and the aspect ratio of the screw is 32-42:1.

[0015] In the method for preparing the tire sidewall rubber compound as described above, wherein in the third step, the aspect ratio of the screw of the third single-screw extruder is 28-36:1.

[0016] The method for preparing the tire sidewall rubber compound as described above, wherein in the third step, the rotor speed of the first internal mixer is 50-90r / min, the filling factor is 0.3-0.7, the mixing time is 50s-90s, and the upper push bolt pressure is 5-8kg / cm 2 .

[0017] The method for preparing the tire sidewall rubber compound as described above, wherein the rubber compound comprises the following raw material components in parts by weight:

[0018] 25-45 parts of natural rubber, 20-40 parts of butadiene rubber, 8-16 parts of green recycled rubber, 8-15 parts of softener, 8-18 parts of lignin, 20-35 parts of white carbon black, 8-13 parts of silane coupling agent, 2-5 parts of zinc oxide, 1-3 parts of stearic acid, 0-3 parts of antioxidant, 2-5 parts of accelerator, and 2-4 parts of sulfur.

[0019] The preparation method of the tire sidewall rubber material as described above, wherein the softener is any one or more combinations of aromatic oil, cycloparaffin oil, and tall oil; the lignin is any one or more combinations of sulfate lignin, lignin sulfonate, alkali lignin and organic solvent lignin; the silane coupling agent is any one of KH580, KH550, and Si-69; the antioxidant is any one of antioxidant 4010, antioxidant 4010NA, and antioxidant 4020; and the accelerator is any one of accelerator D, accelerator DM, accelerator TMTD, and accelerator CZ.

[0020] In the present invention, vegetable oil is added to the waste rubber powder as a regeneration aid, and regenerated rubber with a high degree of regeneration can be obtained. Due to the chemical structure of the vegetable oil itself, it has a long and flexible higher fatty acid chain, which is easier to penetrate into the three-dimensional cross-linked network of the rubber powder during the regeneration process, so that the rubber powder is fully swollen, and at the same time, it is helpful for the rubber regeneration agent to be dispersed into the cross-linked network of the rubber powder, and then the regenerated rubber with a good desulfurization effect is obtained under conditions such as mechanical shearing. Garlic juice or lemon peel juice is selected, and a room-temperature type rubber regeneration agent that can use a chemical substitution reaction to crack the sulfur cross-linking bond in the vulcanized rubber can limit the damage to the main chain of the rubber molecule by oxidation, and can also use a mechanical processing method at room temperature to make the rubber material plastic and maintain good physical properties. This ensures that the prepared green regenerated rubber can meet its mechanical performance requirements when applied to the tire sidewall rubber material, and at the same time, no harmful gases such as hydrogen sulfide are generated, reducing the generation of odor and pollution to the environment. The use of lignin to partially replace white carbon black can not only improve the reinforcement performance of the rubber and reduce the amount of white carbon black, but also has a certain anti-aging effect, which can reduce the use of antioxidants in the rubber.

[0021] Since the softener selected in the present invention is in liquid state at room temperature, it can be mixed with the rubber powder without an additional heating device. When the rubber enters the stirring and mixing device, the rubber powder particles and the rubber powder and the stirring device generate heat due to self-friction under high rotation speed conditions, so that the material is heated up, and the waste rubber powder can be initially de-crosslinked. When the initially de-crosslinked material enters the screw extruder, it does not require a high heating temperature and a large screw aspect ratio. The strong shearing effect of the screw can be used to achieve final desulfurization, and the overall energy consumption is low. In addition, the preparation of the lignin composition and the preparation of the green regenerated rubber are carried out simultaneously. After the preparation of the green regenerated rubber is completed, it does not need to be cooled and directly enters the second twin-screw extruder to mix with the lignin composition and complete the silanization reaction, which not only improves the preparation efficiency, but also reduces the use of energy consumption. When the material enters the third single-screw extruder, on the one hand, the material is cooled, and on the other hand, zinc oxide, stearic acid, antioxidants, etc. are added for mixing to prepare for the vulcanization of the rubber.

[0022] In the preparation process of the green reclaimed rubber of the present invention, no chemical additives are used, and the regeneration temperature is low, which effectively reduces the generation of the odor of the reclaimed rubber and does not affect its use in the tire sidewall rubber. Since the green reclaimed rubber is added to the tire sidewall rubber formula, the use amount of natural rubber and butadiene rubber can be reduced, thereby reducing the impact of the odor caused by the amine derivatives and fatty acids after the protein decomposition inside the natural rubber and the organic solvents and catalyst residues used in the synthesis process of the synthetic rubber. DETAILED DESCRIPTION

[0023] The method for preparing the tire sidewall rubber material of the present invention can be made of the following materials and components, but is not limited to the following materials and components, for example: waste rubber powder, garlic juice, soybean oil, natural rubber, etc.

[0024] The specific embodiment of the method for preparing the tire sidewall rubber material according to the embodiment of the present invention is as follows.

[0025] Example 1

[0026] The first step: put the waste rubber powder, garlic juice and soybean oil into a stirring and mixing device in a mass ratio of 100:4:6, stir for 4 minutes, and when the material temperature reaches 115°C, discharge the material and send it to the first twin-screw extruder through a conveying device. The screw aspect ratio is 24:1. The temperature of the screw extruder is controlled at 136°C and reacted for 2 minutes to prepare green recycled rubber.

[0027] Step 2: Put 25 parts of natural rubber, 30 parts of butadiene rubber, 10 parts of cycloparaffin oil, 8 parts of sulfate lignin, 20 parts of white carbon black and 8 parts of silane coupling agent KH580 into a stirring and mixing device, stir for 2 minutes, and discharge the material when the temperature of the rubber reaches 109°C.

[0028] The third step: 10 parts of the rubber compound prepared in the first step are sent to the second twin-screw extruder through a conveying device, the aspect ratio of the screw is 36:1, and the material obtained by stirring and mixing in the second step is added to the mixing section of the extruder through a side feeding device. The temperature of the mixing section is 115°C, the temperature of the reaction section is 148°C, and the temperature of the cooling section is 120°C. After reacting for 3 minutes, the material is sent to the third single-screw extruder. The aspect ratio of the screw of the third single-screw extruder is 28:1. The temperature of the screw extruder is controlled to be 70°C. 2 parts of zinc oxide, 1 part of stearic acid, and 1 part of antioxidant 4010 are put into the extruder through a feeding device. After mixing for 2 minutes, the material is discharged and sent to the first internal mixer. 2 parts of sulfur and 3 parts of accelerator D are added and mixed to 87°C for discharge. The mill is opened for sheeting, cooling and stacking.

[0029] When the initially de-crosslinked material enters the third screw extruder, high heating temperature and large screw aspect ratio are not required. The strong shearing effect of the screw can be used to de-crosslink the rubber molecular chain under low temperature conditions. The rubber main chain breaks less, the overall energy consumption is low, and the mechanical properties of the recycled rubber are good.

[0030] Example 2

[0031] The first step: put the waste rubber powder, garlic juice and rapeseed oil into a stirring and mixing device in a mass ratio of 100:4:5, stir for 4 minutes, and when the material temperature reaches 120°C, discharge the material and send it to the first twin-screw extruder through a conveying device. The screw aspect ratio is 28:1. The temperature of the screw extruder is controlled at 142°C and reacted for 2 minutes to prepare green recycled rubber.

[0032] Step 2: Put 28 parts of natural rubber, 32 parts of butadiene rubber, 12 parts of cycloparaffin oil, 10 parts of sulfate lignin, 23 parts of white carbon black, and 10 parts of silane coupling agent KH580 into a stirring and mixing device, stir for 2 minutes, and discharge the material when the rubber temperature reaches 118°C.

[0033] The third step: 15 parts of the rubber compound prepared in the first step are sent to the second twin-screw extruder through the conveying device, the aspect ratio of the screw is 36:1, and the material obtained by stirring and mixing in the second step is added to the mixing section of the extruder through the side feeding device. The temperature of the mixing section is 120°C, the temperature of the reaction section is 150°C, and the temperature of the cooling section is 116°C. After reacting for 3 minutes, the material is sent to the third single-screw extruder, the aspect ratio of the screw is 28:1, and the temperature of the screw extruder is controlled to be 73°C. 2 parts of zinc oxide, 1 part of stearic acid, and 1 part of antioxidant 4020 are put into the extruder through the feeding device, mixed for 2 minutes and then discharged, and sent to the first internal mixer, 2 parts of sulfur and 3 parts of accelerator CZ are added, and the mixture is mixed to 82°C for discharge, the mill is opened for sheeting, and the pieces are cooled and stacked.

[0034] Example 3

[0035] Step 1: Put waste rubber powder, lemon peel juice and rapeseed oil into a stirring and mixing device in a mass ratio of 100:6:8, stir for 5 minutes, and when the material temperature reaches 124°C, discharge the material and send it to the first twin-screw extruder through a conveying device. The screw aspect ratio is 28:1. The temperature of the screw extruder is controlled at 148°C and reacted for 3 minutes to prepare green recycled rubber.

[0036] Step 2: Add 33 parts of natural rubber, 26 parts of butadiene rubber, 10 parts of aromatic oil, 11 parts of alkali lignin, 25 parts of white carbon black and 11 parts of silane coupling agent KH550 into a stirring and mixing device, stir for 2 minutes, and discharge the material when the temperature of the rubber reaches 116°C.

[0037] The third step: 16 parts of the rubber compound prepared in the first step are sent to the second twin-screw extruder through the conveying device, the aspect ratio of the screw is 36:1, and the material obtained by stirring and mixing in the second step is added to the mixing section of the extruder through the side feeding device. The temperature of the mixing section is 122°C, the temperature of the reaction section is 148°C, and the temperature of the cooling section is 112°C. After reacting for 3 minutes, the material is sent to the third single-screw extruder, the aspect ratio of the screw is 32:1, and the temperature of the screw extruder is controlled to be 70°C. 2 parts of zinc oxide, 1 part of stearic acid, and 1 part of antioxidant 4020 are put into the extruder through the feeding device, mixed for 2 minutes and then discharged, and sent to the first internal mixer, 2 parts of sulfur and 3 parts of accelerator CZ are added to mix to 82°C for discharge, the mill is opened for sheeting, and the sheets are cooled and stacked.

[0038] The performance test results of the above embodiments are shown in Table 1.

[0039] Table 1 Rubber performance test results

[0040] Test items Example 1 Example 2 Example 3 300% constant tensile stress / MPa 7.4 7.6 7.7 Tensile strength / MPa 18.8 18.9 19.2 Elongation at break / % 676 678 681 Hardness / Shore A 54 55 57 Tear strength (N / mm) 133 135 136 400,000 flex cracks No cracks No cracks No cracks

[0041] It can be seen from the above table that the formulas of Example 1, Example 2 and Example 3 can meet the requirements of tire sidewall rubber materials.

[0042] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages and disadvantages of the embodiments. Through the description of the above implementation methods, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of some deformations plus the necessary general technology superposition; of course, it can also be implemented by simplifying some important technical features. Based on this understanding, the technical solution of the present invention is essentially or contributes to the prior art in the following aspects: the overall structure and connection method, and the structure described in each embodiment of the present invention.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a tire sidewall rubber material, characterized in that: The following steps are involved: Step 1: Preparation of green recycled rubber: Put waste rubber powder, biomass A and biomass B into a stirring and mixing device according to a certain mass ratio, stir for 4-7 minutes, and when the material temperature reaches 110-130°C, discharge the material and send it to the first twin-screw extruder through a conveying device. Control the temperature of the screw extruder to 130°C-155°C, react for 2min-4min, and prepare green recycled rubber; Step 2: Preparation of lignin composition: natural rubber, butadiene rubber, softener, lignin, white carbon black and silane coupling agent are put into a stirring and mixing device, stirred for 1-3 minutes, and discharged when the temperature of the rubber reaches 100°C-120°C; The third step is to prepare the rubber compound for the tire sidewall; the rubber compound prepared in the first step is fed into the second twin-screw extruder through a conveying device, the material obtained by stirring and mixing in the second step is added into the mixing section of the extruder through a side feeding device, the temperature of the extruder is controlled to be 100°C-155°C, the reaction is carried out for 3min-5min, the material is fed into the third single-screw extruder, the temperature of the screw extruder is controlled to be 70°C-85°C, zinc oxide, stearic acid and antioxidant are put into the extruder through a feeding device, mixed for 2-4min and then discharged, fed into the first internal mixer, sulfur and accelerator are added, mixed to 80-100°C and discharged, and the tire sidewall rubber compound is obtained by opening the mixer; In the first step, the mass ratio of waste rubber powder, biomass A and biomass B is 100:3-10:4-8; the waste rubber powder is a mixture of any one or more of waste tire full tire rubber powder and waste tire tread rubber powder, and the mesh size of the waste rubber powder is 20-80 meshes; biomass A is a plant regeneration agent, including any one or more of garlic juice and lemon peel juice; biomass B is any one or more of soybean oil, castor oil, rapeseed oil and palm oil.

2. The method for preparing a tire sidewall rubber compound according to claim 1, characterized in that: In the first step, the length-to-diameter ratio of the screw of the first twin-screw extruder is 24-32:

1.

3. The method for preparing a tire sidewall rubber compound according to claim 1, characterized in that: In the third step, the mixing section temperature of the second twin-screw extruder is 110°C-125°C, the reaction section temperature is 145°C-155°C, the cooling section temperature is 110°C-120°C, and the aspect ratio of the screw is 32-42:

1.

4. The method for preparing a tire sidewall rubber compound according to claim 1, characterized in that: In the third step, the length-to-diameter ratio of the screw of the third single-screw extruder is 28-36:

1.

5. The method for preparing a tire sidewall rubber compound according to claim 1, characterized in that: In the third step, the rotor speed of the first mixer is 50-90r / min, the filling factor is 0.3-0.7, the mixing time is 50s-90s, and the upper push bolt pressure is 5-8kg / cm 2 .

6. The method for preparing a tire sidewall rubber compound according to claim 1, characterized in that: The rubber material comprises the following raw material components in parts by weight: 25-45 parts of natural rubber, 20-40 parts of butadiene rubber, 8-16 parts of green recycled rubber, 8-15 parts of softener, 8-18 parts of lignin, 20-35 parts of white carbon black, 8-13 parts of silane coupling agent, 2-5 parts of zinc oxide, 1-3 parts of stearic acid, 0-3 parts of antioxidant, 2-5 parts of accelerator, and 2-4 parts of sulfur.

7. The method for preparing a tire sidewall rubber compound according to claim 1, characterized in that: The softener is any one or more combinations of aromatic oil, cycloparaffin oil, and tall oil; the lignin is any one or more combinations of sulfate lignin, lignin sulfonate, alkali lignin, and organic solvent lignin; the silane coupling agent is any one of KH580, KH550, and Si-69; the antioxidant is any one of antioxidant 4010, antioxidant 4010NA, and antioxidant 4020; and the accelerator is any one of accelerator D, accelerator DM, accelerator TMTD, and accelerator CZ.